This application pertains to the art of catheters and the use thereof and more particularly relates to angiographic catheters and their use. The invention is particularly applicable to closed tip effect angiographic catheters and will be described with particular reference thereto. It is to be appreciated, however, that the invention has broader applications such as for use with any catheters or other conduits having an open ended tip through which opaque media can be injected into the desired blood vessels or target areas or through which pressures within the blood vessels or target areas may be monitored.
Most angiographic catheters have heretofore included an open ended tip through which an opaque media such as a dye is injected under pressure into a blood vessel or artery. The opening is also used in certain situations to monitor the fluid pressures within the blood vessel where necessary. The opening on the catheter tip proved useful in applications where a guide wire is used to aide in advancing the catheter tip to the desired target vessel. The guide wire itself is positioned within the vessel e.g. femoral artery via the percutaneous technique.
The percutaneous or Seldinger technique involves first puncturing through the outer body tissues and into the vessel of choice such as the femoral artery. After the needle is placed within the vessel of choice, a guide wire, usually formed of stainless steel, is passed through the needle opening and into the vessel. Next, the needle is withdrawn from the vessel and out of the body over the guide which remains lodged in part within the vessel. After the needle has been removed, the open tip end of the catheter is threaded over the guide and into the blood vessel. The guide, at this point, can be withdrawn through the hollow tubular opening of the catheter. At this point in the procedure, a lead end of the catheter is inserted into the vascular system without the necessity to cut open or otherwise sever the blood vessel to gain entry. Often times, however, the guide and catheter are advanced together or otherwise in cooperative unison in order to position the distal end of the open tip catheter through the branching vessel openings to the area to be studied.
In heart studies such as investigations of the coronary arteries, it is necessary most often to study the left ventricle. In this particular application, the flexible catheter may have to be passed over a more rigid guide wire in order to cross a stenotic heart valve and into the ventricle whereat a large amount of opaque media is delivered in a very short period of time. One undesirable result of this large amount of fluid delivery over a short period of time is that the catheter tip "jets" or "whips" within the ventricle. Such movement can dislodge the catheter tip from the ventricle or worse, cause damage to the heart.
In order to provide a catheter which does not exhibit the "jetting" or "whipping" such as present in the open tip catheters, a "pigtail" or curved tip catheter is being used. Although these catheters address the problem of whipping, they are perhaps the most dangerous of all catheters because of their geometry. Numerous side holes are formed in the tip of the catheter in addition to the open tip end which is usually several centimeters downstream of the side holes. Although a saline drip or flush is used to clear the openings in the catheter and prevent clotting as discussed in conjunction with the open tip catheters above, it is not always possible to entirely flush or clear the "pigtail" area. This is because the cross-sectional area of the side hole openings of non-whip catheters such as the pigtail are about twenty times greater than the tip end opening. Accordingly, most of the saline drip or flush never realizes an exit through the tip opening.
The relative ratios of the hole openings in the pigtail catheters are deliberate. The small tip end opening combined with the 360.degree. loop of the tip forward of the side holes encourages a lateral fluid flow. This arrangement maintains the catheter in a stationary position as the opaque media is injected therethrough.
The principle problem with pigtail type catheters is that it is difficult to maintain the catheter tip free of blood clots forming thereat. In addition, the pigtail catheters are rather difficult to pass over a guide wire which is used to introduce the catheter into the entry vessel.
The present invention contemplates a new and improved closed tip effect angiographic catheter apparatus which overcomes all of the above referred problems and others and provides an angiographic catheter combining the best features of both the closed and open tip catheters described above.